Sabrina Lei checks her phone during the StartX event, where Acton discussed his experience founding WhatsApp.

Photo: James Tensuan, The Chronicle

Sabrina Lei checks her phone during the StartX event, where Acton...

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WhatsAPP co-founder Brian Acton speaks to the press in Palo Alto, Calif. on Wednesday, June 4, 2014. The talk was part of a closing night party for StartX, an incubator at Stanford University.

Photo: James Tensuan, The Chronicle

WhatsAPP co-founder Brian Acton speaks to the press in Palo Alto,...

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WhatsAPP co-founder Brian Acton, left, speaks with Cameron Teitelman during a discussion in Palo Alto, Calif. on Wednesday, June 4, 2014. The talk was part of a closing night party for StartX, an incubator at Stanford University.

Photo: James Tensuan, The Chronicle

WhatsAPP co-founder Brian Acton, left, speaks with Cameron...

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WhatsAPP co-founder Brain Acton speaks in Palo Alto, Calif. on Wednesday, June 4, 2014. The talk was part of a closing night party for StartX, an incubator at Stanford University.

Photo: James Tensuan, The Chronicle

WhatsAPP co-founder Brain Acton speaks in Palo Alto, Calif. on...

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Discussion attendees chat as WhatsAPP co-founder Brian Acton, left, speaks with Cameron Teitelman in Palo Alto, Calif. on Wednesday, June 4, 2014. The talk was part of a closing night party for StartX, an incubator at Stanford University.

WhatsAPP co-founder Brian Acton, center, talks to staffers before taking part in a discussion in Palo Alto, Calif. on Wednesday, June 4, 2014. The talk was part of a closing night party for StartX, an incubator at Stanford University.

Photo: James Tensuan, The Chronicle

WhatsAPP co-founder Brian Acton, center, talks to staffers before...

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Left to right, WhatsAPP co-founder Brian Acton speaks with Cameron Teitelman and Alexa Lee during a discussion in Palo Alto, Calif. on Wednesday, June 4, 2014. The talk was part of a closing night party for StartX, an incubator at Stanford University.

Aside from the billions of dollars Facebook will soon deposit into Brian Acton's bank account, the co-founder of WhatsApp stands out from Silicon Valley in one simple but significant way.

He's a grown-up.

That's saying a lot, given the recent parade of young techies behaving badly. Since 2013, we've read about them writing grossly misogynistic e-mails to frat buddies, ranting online about homeless people and pitching a sexually vulgar photo-sharing app whose name we can't publish in a family newspaper.

Instead of behaving like a knucklehead, Acton finished a degree at Stanford University, worked a decade at Yahoo, took two years off, then, at the age of 38, started WhatsApp - the messaging company Facebook is buying for $19 billion.

"When working at a company like Yahoo, you learn to dot your I's and cross your T's," the 42-year-old said at a recent StartX event, his first speaking engagement since co-founding WhatsApp in 2009. "You learn a lot about leadership and management from guys who have done it before you. You learn what works and what doesn't. You pay a lot of attention to the fundamentals."

Those fundamentals, he said, include the mundane but crucial aspects of running a business, like behaving professionally and paying bills on time.

"For me, industry experience was beyond important," Acton said. Out of college, "You think 'I'm just going to build a product.' But you have to worry about contracts, human resources and vacation plans. At Yahoo, (WhatsApp co-founder Jan Koum) and I managed hundreds of servers. Nobody wanted to do it but we did it."

StartX is an incubator run by Stanford students.

For a long time, the popular Silicon Valley narrative has been that of pimple-faced teenagers cashing enormous paychecks for creating code in their bedrooms. Or college dropouts like Bill Gates and Mark Zuckerberg defying conventional wisdom to change the world - earning billions in the process.

Talent, it seems, trumps everything else, including maturity, common sense and good judgment. Genius cannot wait for life to catch up.

We've heard this story before. Think about the Cleveland Cavaliers drafting LeBron James out of high school. Things obviously turned out OK for him. But for every LeBron, we get a couple of J.R. Smiths, talented youngsters suddenly flush with cash who make boneheaded decisions.

The line between immature athletes and immature entrepreneurs is not as thick as we'd like to believe. Officials at Stanford, Acton's alma mater, seem acutely aware of this. Amid revelations that Snapchat co-founder and Stanford dropout Evan Spiegel wrote e-mails as a student that degraded women, school provost John Etchemendy sent a letter to all undergraduates, urging them to learn from Speigel's mistakes. "Members of our community should learn now, not many years from now, how abhorrent those attitudes are, whether real or feigned," Etchemendy wrote, according to tech gossip website Valleywag.

As Acton's career demonstrates, professional and personal maturity beget each other. The DNA of WhatsApp reflects the discipline and seriousness of Acton and Koum. The guiding principle of the service, and perhaps its greatest strategic advantage over competitors, Acton says, is that it must be useful to the broadest number of people.

Acton said the WhatsApp has not been as successful in Asia, partly because the company resisted adding cartoon iconography to its messaging service, childish characters and stickers that are especially popular in China, Taiwan and Japan.

The technology "just effing works," he said. "It works robustly in a heterogeneous world that's not so robust. We don't think in terms of demographics. Whether it's a grandmother in Brazil or a teenager in the Netherlands, I want them to talk to one another. I think people respect that."

When asked whether he would advise students today to drop out of Stanford to start companies, Acton said he wouldn't encourage it.

"The clock is not ticking that fast," he said. "I started WhatsApp when I was 38 years old. Opportunity is available to us at all ages and walks of life."